1. Field of the Invention
This invention relates to a method of and an apparatus for separating coal and other minerals from refuge as found in gob piles containing coal or from mining especially dirty coal. The present invention utilizes gravitational separation of the various components in the raw coal material, which is assisted by agitating a mixture of the raw coal material in water.
2. Description of the Prior Art
There are numerous known methods and systems for separating selected particulate material from mixtures of liquids and solids, including separating coal or ore into two products, according to their specific gravity. For example U.S. Pat. No. 3,410,407 proposes a method and apparatus for separating coal or ore into two products according to their specific gravity by the use of an apparatus including a washing tank with a sloping front wall, a sloping rear wall and sides which is filled with a liquid having a particular specific gravity. This method is disadvantageous in that is requires the use of a liquid suspension having a specific gravity of, for example, 1.5. Also, the procedures of this patent require a quiescent zone to be formed within the washing tank, the construction of which necessitates floatation on the surface of the liquid suspension of coal having a specific gravity lower than that of the liquid suspension.
U.S. Pat. No. 4,222,857 proposes an apparatus for separating a mixture of solids, utilizing an electric, double layer between two phases which are charged relative to one another, which is brought about by the reaction of a special chemical reagent. This U.S. patent uitlizes a trough-shaped vessel with substantially quiescent low conditions. Procedures of this patent are complicated and require the use of a special chemical reagent. Also, the design of the trough-shaped vessel is inflexible in that it cannot be adjusted to accommodate fluctuations in flow rates and, in particular, fluctuations in the amount of materials to be separated.
Further, the foregoing patents by the use of quiescent conditions require precise maintenance of flow conditions which is necessary for the delicate gravity separation upon which their inventions are based.